Synchronize priv-instr-table.tex with the Manual (#99)

This commit roughly synchronizes privileged instruction table with the ISA
Manual with slight instruction order modifications, expecting instruction
tables in the ISA Manual are fully generated by riscv-opcodes,
not modified by hand.

This is based on:

*   riscv/riscv-isa-manual: commit f30a5f6de685
    ("Update chapters 2 and 7 for Hypervisor v0.6")
*   riscv/riscv-opcodes: commit 65af4131
    ("Virtual memory updates (#76)")